RFR: 8079408: Reimplement TraceClassLoading, TraceClassUnloading, and TraceClassLoaderData with Unified Logging.

[Max Ockner]

Hello again,
I have responded to the last round of feedback.

Some of the tests affected by the new logging output have been changed 
to look for the appropriate messages.
Webrevs:
[hotspot] http://cr.openjdk.java.net/~mockner/classload.06
[jdk] http://cr.openjdk.java.net/~mockner/8079408.jdk/

I have made all of the recommended changes to the source, and I have 
fixed all affected tests from Dan's list. I have also fixed any test 
which uses "-verbose:class" and looks for the old output from 
TraceClassLoading or TraceClassUnloading.

Though Ioi suggested I change my new test, I have not done that. I was 
recommended to copy from runtime/ClassUnload/UnloadTest.java instead of 
rolling my own test for class unloading. I mentioned that it was tricky 
to make the new test work, but it was tricky because I was trying to 
copy from UnloadTest.java. This test refers to a class "test.Empty" from 
a "classes" library, but the new test has a processBuilder which I think 
does not play nicely with the class path for  "test.Empty". In the end 
it was much easier to hardcode the entire test into one place than to 
follow UnloadTest.java and refer to extra libraries.

Thanks,
Max